The development of immunoaffinity chromatography for the isolation of highly purified non-degraded (homogeneous) bovine GFA protein will allow a major effort towards characterization. Immunoaffinity chromatography and the anti-neurofilament sera which have become recently available will provide useful tools or the comparison of neurofilament and GFA proteins, at present a controversial issue in the literature. Full use will be made of the newly produced neurofilament antisera for studies on nerve growth and differentiation in vivo. Work on reaggregating and monolayer cultures of dissociated brain cells will be continued in the newly established tissue culture laboratory at the West Roxbury Veterans Administration Hospital. In addition, two clones neurofilament protein-producing of C/300 neuroblastoma will be used for metabolic studies and to investigate the regulatory factors in neurofilament assembly.